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https://www.readbyqxmd.com/read/29333991/evaluation-of-a-portable-gas-chromatograph-with-photoionization-detector-under-variations-of-voc-concentration-temperature-and-relative-humidity
#1
Jhy-Charm Soo, Eun Gyung Lee, Ryan F LeBouf, Michael L Kashon, William Chisholm, Martin Harper
The objective of this present study was to evaluate the performance of a portable gas chromatograph ─ photoionization detector (GC-PID), under various test conditions to determine if it could be used in occupational settings. A mixture of seven volatile organic compounds (VOCs) - acetone, ethylbenzene, methyl isobutyl ketone, toluene, m-xylene, p-xylene, and o-xylene - was selected because its components are commonly present in paint manufacturing industries. A full-factorial combination of four concentration levels (exposure scenarios) of VOC mixtures, three different temperatures (25˚C, 30˚C, and 35˚C), and three relative humidities (RHs; 25%, 50%, and 75%) was conducted in a full- size controlled environmental chamber...
January 15, 2018: Journal of Occupational and Environmental Hygiene
https://www.readbyqxmd.com/read/29333851/oxygen-vacancy-dynamics-at-room-temperature-in-oxide-heterostructures
#2
Shanyong Bao, Jing Ma, Teng Yang, Mingfeng Chen, Jiahui Chen, Shengli Pang, Ce-Wen Nan, Chonglin Chen
Oxygen vacancy dynamic behavior at room temperature in complex oxides was carefully explored by using a combining approach of ion liquid gating technique and resistance measurements. Heterostructures of PrBaCo2O5+δ/Gd2O3-doped CeO2 epitaxial thin films were fabricated on (001) Y2O3-stabilized ZrO2 single crystal substrates for systematically investigating the oxygen redox dynamics. The oxygen dynamic change as response to the gating voltage and duration were precisely detected by in situ resistance measurements...
January 15, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29332994/application-of-the-advanced-distillation-curve-method-to-the-comparison-of-diesel-fuel-oxygenates-2-5-7-10-tetraoxaundecane-tou-2-4-7-9-tetraoxadecane-tod-and-ethanol-fatty-acid-methyl-ester-fame-mixtures
#3
Jessica L Burger, Tara M Lovestead, Mark LaFollette, Thomas J Bruno
Although they are amongst the most efficient engine types, compression-ignition engines have difficulties achieving acceptable particulate emission and NOx formation. Indeed, catalytic after-treatment of diesel exhaust has become common and current efforts to reformulate diesel fuels have concentrated on the incorporation of oxygenates into the fuel. One of the best ways to characterize changes to a fuel upon the addition of oxygenates is to examine the volatility of the fuel mixture. In this paper, we present the volatility, as measured by the advanced distillation curve method, of a prototype diesel fuel with novel diesel fuel oxygenates: 2,5,7,10-tetraoxaundecane (TOU), 2,4,7,9-tetraoxadecane (TOD), and ethanol/fatty acid methyl ester (FAME) mixtures...
August 17, 2017: Energy & Fuels: An American Chemical Society Journal
https://www.readbyqxmd.com/read/29331893/ambient-volatile-organic-compounds-vocs-in-communities-of-the-athabasca-oil-sands-region-sources-and-screening-health-risk-assessment
#4
Md Aynul Bari, Warren B Kindzierski
An investigation of ambient levels and sources of volatile organic compounds (VOCs) and associated public health risks was carried out at two northern Alberta oil sands communities (Fort McKay and Fort McMurray located < 25 km and >30 km from oil sands development, respectively) for the period January 2010-March 2015. Levels of total detected VOCs were comparatively similar at both communities (Fort McKay: geometric mean = 22.8 μg/m3, interquartile range, IQR = 13.8-41 μg/m3); (Fort McMurray: geometric mean = 23...
January 11, 2018: Environmental Pollution
https://www.readbyqxmd.com/read/29331863/airborne-volatile-aromatic-hydrocarbons-at-an-urban-monitoring-station-in-korea-from-2013-to-2015
#5
Azmatullah Khan, Jan E Szulejko, Ki-Hyun Kim, Richard J C Brown
The concentrations of C6-C10 volatile aromatic hydrocarbons (AHCs) in air were measured at an urban air quality monitoring station in Jong-Ro, Seoul, Korea, between 2013 and 2015. Their temporal patterns (e.g., diurnal, intraweek, daily) were assessed individually and collectively as groups of benzene, toluene, ethylbenzene, styrene, and xylene (BTESX); total aliphatic hydrocarbon (TALHC: C2-C12); total aromatic hydrocarbon (TARHC: C6-C10); and total hydrocarbon (THC: C2-C12). The highest mean AHC concentrations over the 3-year study (in ppb (v/v)) were observed for toluene (6...
January 11, 2018: Journal of Environmental Management
https://www.readbyqxmd.com/read/29331811/volatile-organic-compounds-vocs-removal-in-non-thermal-plasma-double-dielectric-barrier-discharge-reactor
#6
Muhammad Farooq Mustafa, Xindi Fu, Yanjun Liu, Yawar Abbas, Hongtao Wang, Wenjing Lu
Non-thermal plasma (NTP) an emerging technology to treat volatile organic compounds (VOCs) present in unhygienic point source air streams. In present study, double dielectric barrier discharge (DDBD) reactors were used for the first time to evaluate the removal efficiency of VOCs mixture of different nature at constant experimental conditions (input power 16-65.8 W, VOCs mixture feeding rate 1-6 L/min, 100-101 ppm inlet concentration of individual VOC). Reactor A and B with discharge gap at 6 mm and 3 mm respectively, were used in current study...
January 9, 2018: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29331743/preliminary-investigation-of-human-exhaled-breath-for-tuberculosis-diagnosis-by-multidimensional-gas-chromatography-time-of-flight-mass-spectrometry-and-machine-learning
#7
Marco Beccaria, Theodore R Mellors, Jacky S Petion, Christiaan A Rees, Mavra Nasir, Hannah K Systrom, Jean W Sairistil, Marc-Antoine Jean-Juste, Vanessa Rivera, Kerline Lavoile, Patrice Severe, Jean W Pape, Peter F Wright, Jane E Hill
Tuberculosis (TB) remains a global public health malady that claims almost 1.8 million lives annually. Diagnosis of TB represents perhaps one of the most challenging aspects of tuberculosis control. Gold standards for diagnosis of active TB (culture and nucleic acid amplification) are sputum-dependent, however, in up to a third of TB cases, an adequate biological sputum sample is not readily available. The analysis of exhaled breath, as an alternative to sputum-dependent tests, has the potential to provide a simple, fast, and non-invasive, and ready-available diagnostic service that could positively change TB detection...
January 4, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/29331718/partition-of-zn-cd-and-pb-during-co-combustion-of-sedum-plumbizincicola-and-sewage-sludge
#8
Feihong Guo, Zhaoping Zhong, Hui Xue
Co-combustion of sedum plumbizincicola and sewage sludge was performed in a tubular furnace. The influence of experimental conditions on the partitioning of Zn, Cd, and Pb was investigated. The results showed that 30% sewage sludge was proposed as the optimal ratio for the co-combustion as a compromise between low calorific value and high amount of heavy metal remained in the bottom ash. High temperature increased the volatilization degree of heavy metals, among which the performance of Cd and Pb was obvious than Zn...
January 6, 2018: Chemosphere
https://www.readbyqxmd.com/read/29331219/polycyclic-aromatic-hydrocarbons-in-soils-and-lichen-from-the-western-tibetan-plateau-concentration-profiles-distribution-and-its-influencing-factors
#9
Ruichen Zhou, Ruiqiang Yang, Chuanyong Jing
The Tibetan Plateau (TP) is a huge area and rarely affected by human activity, and is regarded as one of the most remote regions on the earth. Many studies about the long-range atmospheric transport (LRAT) of semi-volatile organic compounds (SVOCs) were conducted in southern and central TP. However, there are very limited studies focused on PAHs in the western TP and the concentrations profiles, distribution and its controlling factors in this area remains unclear. Thus, to explore this knowledge gap, 37 surface soil samples and 23 lichen samples were collected and analyzed for PAHs...
January 10, 2018: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/29331089/modification-of-chrysanthemum-odour-and-taste-with-chrysanthemol-synthase-induces-strong-dual-resistance-against-cotton-aphids
#10
Hao Hu, Jinjin Li, Thierry Delatte, Jacques Vervoort, Liping Gao, Francel Verstappen, Wei Xiong, Jianping Gan, Maarten A Jongsma, Caiyun Wang
Aphids are pests of chrysanthemum that employ plant volatiles to select host plants and ingest cell contents to probe host quality before engaging in prolonged feeding and reproduction. Changes in volatile and non-volatile metabolite profiles can disrupt aphid-plant interactions and provide new methods of pest control. Chrysanthemol synthase (CHS) from Tanacetum cinerariifolium, represents the first committed step in the biosynthesis of pyrethrin ester insecticides, but no biological role for the chrysanthemol product alone has yet been documented...
January 13, 2018: Plant Biotechnology Journal
https://www.readbyqxmd.com/read/29330736/study-on-the-multi-level-resistance-switching-memory-and-memory-state-dependent-photovoltage-in-pt-nd-srtio3-junctions
#11
Shengkai Wang, Xianwen Sun, Guanghui Li, Caihong Jia, Guoqiang Li, Weifeng Zhang
Pt/Nd:SrTiO3 (STO)/In devices were fabricated by depositing Schottky-contact Pt and Ohmic-contact In electrodes on a single crystal STO with Nd doping. The Pt/Nd:STO/In devices show multi-level resistance-switching (RS) memory and memory-state-dependent photovoltage (PV) effects, which can be controlled by the applied pulse width or magnitude. Both the RS and PV are related to the bias-induced modulation of the interface barrier, both in height and width, at the Pt/Nd:STO interface. The results establish a strong connection between the RS/PV effects and the modulation of the Nd:STO interface triggered by applied electric field and provide a new route by using an open-circuit voltage for non-destructively sensing multiple non-volatile memory states...
January 12, 2018: Nanoscale Research Letters
https://www.readbyqxmd.com/read/29330694/volatile-compounds-from-beneficial-or-pathogenic-bacteria-differentially-regulate-root-exudation-transcription-of-iron-transporters-and-defense-signaling-pathways-in-sorghum-bicolor
#12
Erasto Hernández-Calderón, Maria Elizabeth Aviles-Garcia, Diana Yazmín Castulo-Rubio, Lourdes Macías-Rodríguez, Vicente Montejano Ramírez, Gustavo Santoyo, José López-Bucio, Eduardo Valencia-Cantero
Our results show that Sorghum bicolor is able to recognize bacteria through its volatile compounds and differentially respond to beneficial or pathogens via eliciting nutritional or defense adaptive traits. Plants establish beneficial, harmful, or neutral relationships with bacteria. Plant growth promoting rhizobacteria (PGPR) emit volatile compounds (VCs), which may act as molecular cues influencing plant development, nutrition, and/or defense. In this study, we compared the effects of VCs produced by bacteria with different lifestyles, including Arthrobacter agilis UMCV2, Bacillus methylotrophicus M4-96, Sinorhizobium meliloti 1021, the plant pathogen Pseudomonas aeruginosa PAO1, and the commensal rhizobacterium Bacillus sp...
January 12, 2018: Plant Molecular Biology
https://www.readbyqxmd.com/read/29330538/flux-of-the-biogenic-volatiles-isoprene-and-dimethyl-sulfide-from-an-oligotrophic-lake
#13
Michael Steinke, Bettina Hodapp, Rameez Subhan, Thomas G Bell, Dominik Martin-Creuzburg
Biogenic volatile organic compounds (BVOCs) affect atmospheric chemistry, climate and regional air quality in terrestrial and marine atmospheres. Although isoprene is a major BVOC produced in vascular plants, and marine phototrophs release dimethyl sulfide (DMS), lakes have been widely ignored for their production. Here we demonstrate that oligotrophic Lake Constance, a model for north temperate deep lakes, emits both volatiles to the atmosphere. Depth profiles indicated that highest concentrations of isoprene and DMS were associated with the chlorophyll maximum, suggesting that their production is closely linked to phototrophic processes...
January 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29329851/chemical-characterization-of-myrciaria-floribunda-h-west-ex-willd-fruit
#14
Luciana Mouta de Oliveira, Alexandre Porte, Ronoel Luiz de Oliveira Godoy, Marcelo da Costa Souza, Sidney Pacheco, Manuela Cristina Pessanha de Araujo Santiago, Ana Cristina Miranda Senna Gouvêa, Luzimar da Silva de Mattos do Nascimento, Renata Galhardo Borguini
M. floribunda fruit was studied to characterize its chemical composition. The chemical composition, bioactive compounds, antioxidant activity and volatiles of the fruit were determined. The chemical composition was determined according to AOAC and AOCS, the bioactive compounds by HPLC, the volatiles by GCMS and the antioxidant activity by ABTS+ and DPPH methods. The chemical composition of the freeze-dried fruit was 1.89 g·100 g-1, 2.43 g·100 g-1, 4.78 g·100 g-1 and 90.89 g·100 g-1 of ashes, lipids, proteins and total carbohydrates on a dry base, respectively...
May 15, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29329850/gc-ms-profiling-descriptive-sensory-analysis-and-consumer-acceptance-of-costa-rican-papaya-carica-papaya-l-fruit-purees
#15
Veronika M Lieb, Patricia Esquivel, Elba Cubero Castillo, Reinhold Carle, Christof B Steingass
Volatiles of papaya purees from four Costa Rican cultivars were analysed by solid-phase microextraction and gas chromatography-mass spectrometry. A total of 83 volatiles was assigned in the purees, of which 19 were detected for the first time as papaya constituents. As revealed by multivariate statistics, i.e., principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), the purees may be allocated to terpene- and lactone-rich ('SH-5'), ester-containing ('Criolla'), and intermediate chemotypes ('Pococí' and 'Silvestre')...
May 15, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29329710/hydride-generation-coupled-with-thioglycolic-acid-coated-gold-nanoparticles-as-simple-and-sensitive-headspace-colorimetric-assay-for-visual-detection-of-sb-iii
#16
Tesfaye Tolessa, Zhi-Qiang Tan, Jing-Fu Liu
Antimony (Sb) is a toxic element which causes different health problems including cardiac problems and lung cancer in humans, and its levels in surface water can be noticeably increased to 100 μg/L typically in the proximity of anthropogenic sources. Thus, besides instrumental techniques, it is of great significance to develop a simple, sensitive and selective analytical method for direct analysis of Sb(III) at trace level without the need of any expensive and/or complicated instrumentations and sample preparation processes...
April 3, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29329229/chemical-composition-and-evaluation-of-the-biological-properties-of-the-essential-oil-of-the-dietary-phytochemical-lippia-citriodora
#17
Eleni Fitsiou, Gregoria Mitropoulou, Katerina Spyridopoulou, Manolis Vamvakias, Haido Bardouki, Alex Galanis, Katerina Chlichlia, Yiannis Kourkoutas, Mihalis Ι Panayiotidis, Aglaia Pappa
The aim of the study was to characterize the chemical composition and biological properties of the essential oil from the plant Lippia citriodora grown in Greece. The essential oil volatiles were analyzed by gas chromatography-mass spectrometry GC-MS indicating citral as the major component. Τhe antimicrobial properties were assayed using the disk diffusion method and the minimum inhibitory and non-inhibitory concentration values were determined. Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger were sensitive to Lippia citriodora oil, but not Escherichia coli, Salmonella Enteritidis, Salmonella typhimurium, and Pseudomonas fragi...
January 12, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29329227/fermentation-guided-natural-products-isolation-of-a-grape-berry-triacylglyceride-that-enhances-ethyl-ester-production
#18
Christopher L Blackford, Eric G Dennis, Robert A Keyzers, Claudia Schueuermann, Robert D Trengove, Paul K Boss
A full understanding of the origin, formation and degradation of volatile compounds that contribute to wine aroma is required before wine style can be effectively managed. Fractionation of grapes represents a convenient and robust method to simplify the grape matrix to enhance our understanding of the grape contribution to volatile compound production during yeast fermentation. In this study, acetone extracts of both Riesling and Cabernet Sauvignon grape berries were fractionated and model wines produced by spiking aliquots of these grape fractions into model grape juice must and fermented...
January 12, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29328808/effective-prevention-of-oxidative-deterioration-of-fish-oil-focus-on-flavor-deterioration
#19
Kazuo Miyashita, Mariko Uemura, Masashi Hosokawa
Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), both abundant in fish oil, are known to have significant biochemical and physiological effects primarily linked to the improvement of human health, especially cardiovascular and brain health. However, the incorporation of fish oil into foods and beverages is often challenging, as fish oil is very easily oxidized and can cause undesirable flavors. This review discusses this rapid formation of the fishy and metallic off-flavors, focusing especially on an early stage of fish oil oxidation...
January 12, 2018: Annual Review of Food Science and Technology
https://www.readbyqxmd.com/read/29327928/one-step-bioconversion-of-fatty-acids-into-c8-c9-volatile-aroma-compounds-by-a-multifunctional-lipoxygenase-cloned-from-pyropia-haitanensis
#20
Zhu-Jun Zhu, Hai-Min Chen, Juanjuan Chen, Rui Yang, Xiao-Jun Yan
The multifunctional lipoxygenase PhLOX cloned from Pyropia haitanensis was expressed in E. coli with 24.4 mg•L-1 yield. PhLOX could catalyze the one-step bioconversion of C18-C22 fatty acids into C8-C9 volatile organic compounds (VOCs), displaying higher catalytic efficiency for eicosenoic and docosenoic acids than for octadecenoic acids. C20:5 was the most suitable substrate among the tested fatty acids. The C8-C9 VOCs were generated in good yields from fatty acids, e.g., 2E-nonenal from C20:4, and 2E,6Z-nonadienal from C20:5...
January 12, 2018: Journal of Agricultural and Food Chemistry
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